Question: On the first 4 quizzes of her language class, Tiffany got an average score of 82. What does she need on the next quiz to have an overall average of 85?
Let her score on the next quiz be $x$ The sum of all of her scores is then $4 \cdot 82 + x$ The same sum must also be equal to $5 \cdot 85$ Solve: $x = 5 \cdot 85 - 4 \cdot 82 = 97$.